The agent computes exact hole assignments server-side but can only send an
approximate canvas x/y, because the rotation pivot is the DOM wrapper centre
and the wrapper includes a text label the server cannot measure. Under
rotation that left seated parts off by up to ~4 px — enough that a diode
(pins 7.5 pitches apart) half-seated: computeSeating found no hole for the
far pin and it went electrically dead.
resolveSeatPosition corrects it in the browser by pure translation: read
where the anchor pin actually is from live DOM geometry (real pivot), read
where the solver put it, shift the whole part by the difference. Every other
pin follows because pin-to-pin offsets are pivot-free. It never re-solves, so
it cannot slide the part to different holes and the validated netlist holds.
The anchor target is the solver's anchor position in breadboard-element
space, WITH its sub-pitch centroid translation — not the hole centre.
Targeting the centre would re-break the diode (far pin 4.8 px out). Verified
against real rendered geometry in a browser: resistor and diode at 90° both
seat within the intrinsic lattice residual (0.6 / 2.4 px).
Applied via a `seat` payload on the move_component effect (velxio-prod
overlay); this commit is the resolver + tests.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Three changes, all driven by a real project where a 4-digit 7-segment clock
was unreadable and half its parts were not actually seated.
Labels on hover only
--------------------
Eight vertical resistors at 19 px pitch rendered eight 93 px "Resistor 220 Ω"
labels on top of each other, hiding the parts and the breadboard holes; the
SPICE overlay added ~40 more `0uV` pills. Both are now revealed on hover:
hovering a part also lights up the voltages of every wire touching it.
The label is hidden with OPACITY and stays in flow. pinPositionCalculator
derives the rotation pivot from wrapper.offsetHeight, so taking it out of
flow would move the pins of every rotated component in every saved project.
Seat-on-drop
------------
The drag-time magnet only aligned the anchor pin and assumed the rest
followed, which is how parts ended up HALF-seated: some pins in holes, the
rest dead in the air. It looks mounted in a screenshot and silently breaks
the circuit. On release we now re-solve properly — nearest position where
EVERY pin is in a free hole, sliding past occupied columns — via the new
solvePlacement/seatOnDrop. Geometry comes from the element's own pinInfo,
so there is no part whitelist.
Sub-pitch translation
---------------------
solvePlacement first assigned pins to holes at half-pitch, then translates
by the centroid of the residuals before judging fit. Pinning the anchor dead
centre refused every off-lattice footprint: a diode spans 7.5 pitches, so
one leg landed 4.8 px out. Shifted 2.4 px, BOTH legs sit inside tolerance —
what bending the leads does on a real board. Measured over the catalog this
takes seatable parts from 87 to 125 of 152; diodes, transistors, regulators,
optocouplers and flip-flops are rescued with no artwork change.
Staying under SEAT_TOLERANCE (< half pitch) keeps each pin's nearest hole
unambiguous, so computeSeating resolves the same holes and the netlist is
unaffected by the small offset.
Also: refuse a placement that would put two of a part's own pins in one
strip. A column strip — and far worse, a power rail — is a single net, so
such a seating shorts the part to itself. Without it a 7-segment happily
lays its pins across a rail. And deduplicate pin names before solving:
calculatePinPosition resolves by name and returns the first match, so a
board carrying GND x5 collided with itself and was refused outright.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Parts now plug INTO the breadboard instead of using it as a junction box:
- Drag magnetism: while dragging, the part's anchor pin snaps to the
nearest hole center (9 px range, 9.6 px grid) so parts land perfectly
aligned, like Wokwi.
- Seating: every pin within 4 px of a hole gets an invisible zero-length
wire (Wire.bb) from pin to hole — the exact model Wokwi persists as
["r1:1","bb1:6t.b","",["$bb"]]. Electrically they are ordinary
wires, so the netlist builder, digital trace and SPICE need zero
changes; they are simply not rendered and not hit-testable. Seating
re-computes on every move/rotation (updateComponent), and moving the
breadboard carries its seated parts along.
- Resistors auto-rotate to vertical when dragged over a breadboard
(their 58.8 px pin span bridges the center trench rows b-f exactly).
- Seat tolerance 4 px: absorbs the worst element pin-spacing residual
(~1.6 px) while staying under half the hole pitch, so a pin is never
ambiguous between holes.
Wokwi interchange fixes that fell out of the diagram.json research:
- import maps the top-level rotate attr onto properties.rotation
(previously every rotated part imported flat) and export emits it
back as rotate instead of leaking it into attrs;
- $bb / empty-color connections import as bb seating wires and export
back as ["$bb"] entries, so parts-on-breadboard projects round-trip;
- wokwi-breadboard-half aliases to the full breadboard (hole names are
a strict superset, so every connection stays valid).
Breadboard elements now export their pure hole grids and import cleanly
without a DOM (node tests); geometry + store seating covered by
breadboard-snap.test.ts and breadboard-seating.test.ts.
David Montero Crespo